# 计科1915班 0306224505 屠玉宝

def grade(num):
    if num == 100:
        print("满分")
    elif 90 < num < 100:
        print("优")
    elif 80 < num <= 90:
        print("良")
    elif 60 < num <= 80:
        print("中")
    elif num <= 60:
        print("不及格")


if __name__ == '__main__':
    num = int(input("请输入你的成绩："))
    if num < 0 or num > 100:
        print("成绩不存在")
        exit()
    grade(num)
